Cost-effectiveness of a lottery for increasing physicians' responses to a mail survey

To evaluate the cost-effectiveness of a lottery on physicians' responses to a mail survey a randomized controlled trial was conducted with a random sa mple of 1,000 members of the Quebec Federation of General practitioners in 1997 For the first mailing of this survey, each respondent was randomly ass igned to the control or experimental group, which was offered participation in a lottery upon return of the questionnaire. Response rate was 41.2% in the experimental group and 34.8% in the control group, a 6.4% difference (C I95%: 0.6% - 12.6%). The additional cost of the lottery was about Can$500, giving an incremental cost of Can$16 per questionnaire returned. In conclus ion, a lottery resulted in a small but statistically significant increase i n the response rate of physicians to a mail survey. This method may be a co st-effective option when applied to large surveys.